Disposable absorbent articles for acquisition and storage of body exudates (e.g., urine, feces, blood, vaginal discharge, saliva, etc.) are well known in the prior art and have been provided for many uses in various configurations. Typical examples include disposable diapers or incontinence pads which are intended to absorb and retain urine and feces; wound dressings (e.g. bandages) which are intended to absorb and retain blood; and catamenial pads which are intended to absorb and retain menstrual and other vaginal discharges, and prevent body and clothing soiling. In each, the disposable absorbent article absorbs and retains body exudates, thereby preventing the exudates from soiling or otherwise contaminating the area (e.g. the clothes or the wearer) around the body exudates discharge.
In general, disposable absorbent articles have the same basic structure: an absorbent structure, which is encased between a topsheet, which is in contact with the wearer, and a backsheet. The prior art teaches numerous variations of these elements, with each variation being directed to improving one or more specific characteristics of the absorbent article.
A catamenial product (e.g. a sanitary napkin, a pantiliner or a tampon) is distinguishable from other types of absorbent articles in that its materials must absorb, distribute, store, and retain vaginal discharges (e.g. menstrual and other vaginal discharges), which are distinguishable from other types of discharged body exudates, such as urine, which is typically absorbed by a diaper. Urine is characterized as a Newtonian fluid and has a relatively constant viscosity. A vaginal discharge, on the other hand, is a complex and heterogeneous suspension that is characterized as a non-Newtonian fluid (e.g., a fluid that generally does not maintain a constant viscosity throughout and does not follow typical flow patterns because of the high solid content). As will be appreciated, menstrual discharges typically comprise a non-solid or fluid portion, having water, and a solid portion having various elements, such as body tissue fragments, protein aggregates, lipids etc., each of which contribute to the non-Newtonian fluid characteristic. The composition of menstrual discharge varies from woman to woman, and even from day to day with an individual woman.
There are numerous absorbent articles in the prior art with storage components that are interposed between a backsheet and an acquisition component. The acquisition component of these articles typically is a material configured so that it quickly absorbs and wicks exudates away from the wearer and topsheet, and toward and into the storage component. Such articles also are configured so that exudates do not flow back toward the wearer reducing the possibility of "rewetting". This provides comfort for the wearer of the article since the skin of the wearer remains relatively dry. The storage component is a material provided in absorbent articles to absorb exudates from the absorbent component, and that can store and redistribute the absorbed exudates.
Several materials have been developed, especially in the area of disposable diapers, which provide enhanced storage capacity and redistribution properties (e.g. wicking). Examples of such materials include small pore polymeric foam materials, which have a storage capacity of about five (5) times the storage capacity of fiber materials, and about 30 to 50 times its own weight. Unfortunately, these polymeric foam materials have not previously been viable in catmenial products since some of the open spaces are similarly sized to red blood cells, and suspended solids, which are typically found in vaginal discharges. The solid portion of the vaginal discharge tends to block or clog the open spaces which, in turn, limits storage capacity and the redistribution capability therein.
Another material with enhanced storage capacity is a superabsorbing hydrogel material dispersed in fiber matrix which has storage capacity for artificial menstrual fluid from about 8 to about 16 times greater than its own weight, and from about 25 to about 30 times it own weight for urine. Also, the material has a storage capacity from about 2 to about 3 times greater than fiber materials. Like the polymeric foam materials discussed above, superabsorbing polymers dispersed in a fiber matrix were not as viable in catamenial products since the solid portion in vaginal discharge can plate the outer surface of superabsorber particles, which reduces their capacity to absorb and store the discharge. This problem is not unique to polymeric foam materials or superabsorbing hydrogel material in a sheet form or dispersed in fiber matrix, and can exist with any absorbent material having a high concentration of small pores or openings. Examples of such materials include other foams, superabsorbers, sheeted superabsorbers, dense fiber materials and the like.
It is an object of the present invention to provide an absorbent structure that allows the use of highly effective storage materials in absorbent structures.
It is also an object of the present invention to provide an absorbent structure with an extended useful life.
It is another object of the present invention to provide an absorbent structure with increased storage capacity.
It is still another object of the present invention to provide an absorbent structure having improved surface cleanliness to have a good visual appearance.
Another object of the present invention is to provide an absorbent structure having improved protection against soiling in the area around the area of exudate discharge.
Additional objects, advantages and other features of the present invention will be set forth and will become apparent to those skilled in the art upon examination of the following, or may be learned with practice of the invention.